Republican presidential candidate and TV personality Donald Trump arrives by escalator to the tune of "Rockin' In The Free World." Musician Neil Young did not approve of his song choice. Brendan McDermid /Reuters /Landov hide caption

itoggle caption Brendan McDermid /Reuters /Landov

Former U.S. Secretary of State Hillary Clinton Ethan Miller/Getty Images hide caption

itoggle caption Ethan Miller/Getty Images

With less than two years left in his presidency, President Obama has been less scripted and appears less confined by politics. Saul Loeb/AFP/Getty Images hide caption

itoggle caption Saul Loeb/AFP/Getty Images

Hillary Clinton spoke Tuesday at Christ the King United Church of Christ in Florissant, Mo. Whitney Curtis/Getty Images hide caption

itoggle caption Whitney Curtis/Getty Images

In 1981, Bernie Sanders won a 10-vote victory over a Democratic incumbent to become mayor of Burlington, Vt. Donna Light/AP hide caption

itoggle caption Donna Light/AP

Hillary Clinton, featured in a high school yearbook with the student council. Tamara Keith/NPR hide caption

itoggle caption Tamara Keith/NPR

Sen. Bernie Sanders drew a large crowd when he launched his campaign last month in Burlington, Vt., and the crowds have continued. Andy Duback/AP hide caption

itoggle caption Andy Duback/AP